1. Field of the Invention
The present invention relates to a semiconductor device and a manufacturing method of semiconductor devices. In particular, the invention relates to a semiconductor device, and its manufacturing method, that includes a microprocessed silicon substrate upon which a Hall-effect element is mounted.
2. Description of the Related Art
Recently, micromachines, or micro electro mechanical system (MEMS), have been widely used as applications of LSI manufacturing technologies. To prepare a micromachine, a silicon substrate may be subjected to microprocessing technique, and required semiconductor elements are mounted on the processed silicon substrate. In manufacturing the micromachine, for instance, anisotropic etching including wet etching with an alkaline solution is employed to implement the microprocessing of the substrate. By the anisotropic etching, minute recesses can be accurately formed on the silicon substrate, into which semiconductor elements are disposed.
JP-A-No. 2005-277380 discloses an LED package based on the micromachine manufacturing technique. The LED package is obtained by forming a recess (which may often be referred to as “horn” due to its shape) on a silicon substrate by anisotropic etching, and disposing an LED chip on the bottom surface of the recess. The recess is formed by anisotropic etching with respect to the (100) surface of the silicon substrate, and hence includes a side face inclined relative to the bottom surface which is formed by the (111) surface. The side face extends between the (100) surface and the bottom surface. On the bottom surface and the side face is formed an electrode (conductive layer) for electrical connection to the LED chip and various circuit boards. The electrode is formed through depositing a Ti layer (barrier layer) and a Cu layer on the bottom surface the sloped side face, for example by sputtering, and performing a patterning process by etching on the Ti layer and the Cu layer, via a mask formed by photolithography. The LED chip is mounted on the bottom surface of the recess, and then an epoxy resin (sealing resin) is filled in the recess.
When the sealing resin is heated to be cured, the silicon substrate is also subjected to the heat, and thus the silicon substrate and the resin will both undergo thermal distortion. Since the epoxy resin is higher in thermal expansion rate than Si constituting the silicon substrate, the distortion of the sealing resin is greater than that of the silicon substrate. Unfavorably, the difference in thermal distortion may cause a warp in the silicon substrate, and the resulting package may be a defective one depending on the extent of the warp.